1. Field of the Invention
The invention is related to the field of communications, and in particular, to communication antennas.
2. Description of the Prior Art
Most cellular backhaul uses Incumbent local exchange carrier (ILEC) T1 circuits. ILEC circuits are expensive and do not scale economically as cell backhaul demand increases, especially for wireless data and video. Using point-to-point or point-to-multipoint radio or microwave links for cellular backhaul links can be costly. One of the cost drivers is the cost of real estate on cell towers. In this application the term “cell tower” includes all manner of cellular mounting structure, for example building sites, towers, treelike structures, and the like. Cell tower leasing agreements typically charge a fee for each antenna element mounted to the tower, and a fee based on the number of cables running up the tower that attach to the antenna elements.
Therefore there is a need for a system and method that allows multiple antenna elements to be mounted onto a cell tower at a minimum cost.
The spectrum available for the radio and microwave point-to-point and point-to-multipoint links is also restricted. Common carrier bands at 2, 4 and 6 GHz, especially the 4 GHz band, are under utilized today. The original and primary use of the bands was for long distance telecommunication across the US. The long distance links were typically operated by AT&T, MCI and other telephone companies. The long distance radio frequency (RF) links had link distances of 30 miles or more. These long distance links require large antennas. These antennas had to be mounted individually on cell towers and the leasing cost on cell towers is based, in part, on the number of mountings used. The large microwave antennas also created wind loading problems on cell towers. Today these companies and new operators typically utilize fiber optic transcontinental networks for Long Distance telecommunications. Deployment of fiber networks has rendered the 4 GHz band as highly under utilized and available for other uses.
Therefore there is a need for a system and method that utilizes these common carrier bands for point-to-point links.